The present invention relates to a chain belt, and more particularly to a pivot joint for articulation between adjacent sets of chain links in a chain-belt. Various types of pivot means have been utilized for the joining and articulation of chain links, such as cylindrical pivot pins, pin and rocker, etc. wherein the chain links are provided in sets that are interleaved together and have aligned apertures in the links that receive the pivot means. The chain links articulate as the chain wraps around a pulley or sprocket for the chain.
Chain links which are used for the manufacture of chain-belts, combining a chain and a plurality of load blocks, are especially suitable to provide a driving connection between a pair of pulleys, resulting in a variable ratio drive transmission. The load blocks are positioned on the chain between the spaced pivot means and have one or more windows therein receiving the chain links extending therethrough. The load blocks have tapered outer or end surfaces which engage the sheave faces of the pulleys to provide the driving engagement between the pulleys and the chain-belt.
For a single round pin as the pivot means, the ends of the pins could be headed or swaged beyond the outside or guide chain links at both ends of the pin or the guide links could have slightly smaller apertures to provide a force fit with the ends of the pin. In some forms of power transmission chain using a pair of similar pins or a pin and rocker, one of the pin members is longer than the other, and the shorter member is retained in position by guide links flanking the edges of the chain; the guide link having apertures only large enough to receive the longer of the pin members. Then the longer of the pins is press-fit or otherwise secured in the guide link aperture.
Another method of limiting lateral movement of the pins or pin and rocker pivot means is through the use of a locking clip or spring clip. For a locking clip, the ends of the pins or pin and rocker have grooves located slightly beyond the chain links, and a clip engages in the groove or grooves to retain the pins intact. Such a locking clip is shown in U.S. Pat. No. 3,939,721. Where a spring clip is used, a resilient retaining clip extends across the width of the chain with downturned ends that extend over the ends of the pins or pin and rocker and are bent inward below the pin ends as seen in FIG. 9 of U.S. Pat. No. 4,507,106. One problem with either locking clips or spring clips is that clips are difficult to assemble and are prone to breakage, leaving the pins free to move laterally in the link sets. The present invention overcomes the problems relative to retaining the pivot pins in a chain-belt without adding any additional structure thereto.